During a fishing excursion on Pocksha Pond in Lakeville in 1993, Nancy Yeatts spotted an active bald eagle’s nest — a find so rare that she returned to the spot for eight hours a day for almost a week to snap countless photos before reporting her discovery to the state.

It had only been four years earlier that state wildlife officials reported bald eagles were successfully breeding in Massachusetts after the then-endangered species was reintroduced at Quabbin Reservoir in the central part of the state in 1982.

In a one-day survey conducted April 5, Massachusetts wildlife officials and 35 volunteers verified the existence of 30 active bald eagle nests in the state, including four along the Merrimack River and others in communities including Arlington, Framingham, Middleborough, Carver, and Plymouth.

“That’s awesome,” said Joan Walsh, director of bird monitoring at the Massachusetts Audubon Society. “Prior to 1989, it had almost been 100 years before eagles bred here. . . . In Massachusetts, we’re a small place, but we’ve done a great job of saving the landscape. I’m really proud of that number, and it’s going to grow.”

The nest survey, coordinated by the state’s Division of Fisheries and Wildlife (MassWildlife), was only the second of its kind conducted in Massachusetts. Until 2011, MassWildlife conducted individual eagle counts each winter, the last one yielding 104 bald eagles. As the eagle population grew, officials decided it would be more productive to count nests.

Since the survey, bird watchers have reported other eagle and nest sightings to MassWildlife, including one nest in Stoneham. MassWildlife officials welcome and are encouraged by spotters’ reports and expect the final number of nests this spring will surpass last year’s.

Although several local conservation agents said 30 active nests is an impressive number, the state lost two since last year, both of them in Lakeville. One nest was knocked down by strong winds in April, destroying an egg, while the other was abandoned by a pair of eagles, said Yeatts, the conservation agent.

According to Yeatts, “2000 was the last year we had a nest with no baby eagles.” She added that she is optimistic eagles will breed again in Lakeville, home of the Assawompset Pond Complex, connecting to five ponds: Assawompset, Long, Pocksha, Great Quittacas, and Little Quittacas.

Primarily fish eaters, bald eagles prefer to live near open water. Yeatts said there are two pairs of bald eagles in the area that she hopes stick around.

“I can see an eagle every day of my life . . . and it’s wondrous every time; never changes,” she said. “Let’s cross our fingers that we have better nests next year.”

Along the Merrimack River, the fact that four pairs of eagles decided to nest is a testament to how far the river has come since its days of being contaminated by the mills and factories that it powered, said Caroly Shumway, executive director of the Merrimack River Watershed Council. She said pairs have been spotted in Newburyport, Amesbury, Methuen, and Haverhill.

“The bald eagles are a symbol of the beauty and vitality of the river,” Shumway said. “The rivers are cleaner and the fish have come back. Where there are fish, there are eagles.”

Cori Beckwith, Arlington’s conservation administrator, said now is a good time to spot eagles, likely around Mystic Lake, where alewife herring are running.

“I’m thrilled to see them. . . . It’s amazing for an urban area to get that,” Beckwith said. “It’s a testament to this concept of protecting corridors. Wildlife needs areas to meet their needs — nesting, food, to communicate — rather than having isolated little spots.”

Herring are also credited for the presence of bald eagles in Middleborough, said conservation agent Patricia J. Cassady. The area boasts one of the largest herring formations in the state, coming from the Atlantic Ocean, to the Taunton River, the Nemasket River, and ultimately to Assawompset Pond.

“Everybody around here knows they’re flourishing,” she said.

Bald eagles have been wintering in Plymouth for about 10 years, but began to nest and rear their young there only during the past two years, said Casey Shetterly, project manager for the Nature Conservancy’s
Southeastern Massachusetts office in Plymouth.

“To me, it speaks to the environmental health of the region,” she said. “We have a lot of mature forests, we have clean waters, large enough swaths of lands, and land that is connected so they can migrate and move around.”

Bald eagles, whose population declined at alarming rates nationwide starting in the 1950s and 1960s primarily due to the widespread use of the pesticide DDT, are the largest bird of prey native to the state, with a body length of about 3 feet and a wingspan of up to 7 feet. They are born the size of a teacup, and can live up to 30 years, said Walsh, of Mass Audubon.

“It stands as one of the greatest conservation success stories in the world,” Walsh said. “It was important to recover the bald eagle as a measure of national pride. . . . It’s an amazing recovery and something we should all be proud of.”